The addition of hydrolyzed rice straw in xylose fermentation by Pichia stipitis to increase bioethanol production at the pilot-scale

The pretreatment of agricultural biomass by diluted acid is often employed to facilitate the release of monosaccharide for the subsequent enzyme hydrolysis for lignocellulosic ethanol production. However, furfural and hydroxymethylfurfural are usually generated and markedly decrease the yield of pentose fermentation during this pretreatment. In the present study, the enhancement of lignocellulosic ethanol production was successfully demonstrated at pilot scale with extra addition of hydrolyzed rice straw into pentose fermentation by Pichia stiptis. This way has resulted into the increase of P. stiptis cell mass was shown to play a positive role. The ethanol yield, 0.45 g_p/g_s, with the addition of hydrolyzed rice straw in hemicellulosic hydrolysate from plywood, bagasse and bamboo were increase 20–51% to demonstrate the applicability of this technology in a variety of lignocellulosic ethanol processes due to the efficient conversion of xylose.     

The effects of water soluble polymers on paper coating consolidation

The consolidation process of wet paper coating layers has been generally divided into several stages by the definitions of first critical concentration (FCC) and second critical concentration (SCC), however few works have been done on the kinetics of water expelled during drying and its influence on the critical concentrations. In this paper, the effects of three kinds of water soluble polymers, i.e., carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA) and modified coating starch, on the consolidation of model kaolin clay-latex coatings were investigated. On-line water evaporation loss rate, together with the level of FCC and time needed to reach FCC, was characterized. The results showed that water evaporation loss weight increased almost linearly with drying time during the initial wet coating layer consolidation stage. On-line water evaporation rate and the value of FCC decreased with water soluble polymers addition, while the time needed to reach FCC became longer. Among the three polymers studied, CMC was the most effective, then PVA and starch.     

Facile Approach for Preparation of Xylan-based Double-network Hydrogels

In this study, xylan-based double-network (DN) hydrogels (xylan-based DN gels) with excellent mechanical properties were prepared using acrylic acid and acrylamide (AM) based on a DN approach. The first layer network was obtained by grafting and crosslinking polyacrylic acid (PAA) molecular chains onto xylan with ammonium persulfate (APS) as the initiator and N,N''-methylenebisacrylamide (MBA) as the crosslinking agent; this network was subsequently immersed into an aqueous AM monomer in the presence of APS and MBA for the preparation of the second layer network. The results showed that the double networks were crosslinked by covalent bonds and that the mechanical properties of the xylan-based DN gels were enhanced. Thus, the xylan-based DN gels exhibited a maximum compression stress of 24.9 MPa. The xylan-based DN gels could also recover 97% of their original height after 15 repeated compression cycles; this indicates that the xylan-based DN gels possessed high resistance to friction and wear. Therefore, the prepared xylan-based DN gels have considerable potential for tissue engineering applications.     

Controlled‐release drug carriers based hierarchical silica microtubes templated from cellulose acetate nanofibers

We report a facile method to synthesize hollow silica microtubes (SMTs) from electrospun cellulose acetate fiber precursors. Specific surface areas of up to 765 m²/g (Brunauer–Emmett–Teller) were measured for the SMTs, which had a typical wall thickness of ～100 nm and submicron inner diameters. An average pore size of 4.6 nm and pore volume of 0.41 cm³/g were derived from Barrett–Joyner–Halenda fitting, whereas Horvath–Kawazoe pore size distribution analysis revealed microporous median pore size and maximum pore volume of 0.7 nm and 0.18 cm³/g, respectively. The as‐prepared SMTs featuring micro‐ and mesoporous structures in the walls where amino‐functionalized to facilitate a very high drug loading (15% by weight). Drug release profile revealed sustained release rates (79% of acetylsalicylic acid was released after 6 h). It is concluded that the high drug loading and sustained release resulted from the advantageous integration of SMTs' hollow structure and wall mesoporosity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42562.     

The non-trivial role of native xylans on the preparation of TEMPO-oxidized cellulose nanofibrils

Cellulose nanofibrils have become increasingly prized as a raw material toward the preparation of composites due to their specific surface character and biocompatibility. TEMPO-mediated oxidation with post-mechanical treatment has been proposed as a promising method for the preparation of cellulose nanofibrils from cellulosic raw materials. In the current study it was found that the native hemicellulosic components in the raw material played a pivotal chemical role on the kinetics of generation of TEMPO-oxidized cellulose nanofibrils (TOCNs), as well as on thermal stability, and transmittance. The removal of xylans from the original feedstock facilitated not only an increase in both the carboxylate content and water retention value of the TEMPO-oxidized fibers, but also improved the transmittance of subsequently obtained TOCNs suspensions. It was also determined that the presence of xylans in the cellulosic feedstock hindered chemical accessibility through a barrier mechanism in which the TEMPO-mediated oxidation reaction rate was reduced.     

The effect of assorted pretreatments on cellulose of selected vegetable waste and enzymatic hydrolysis

Pretreatment of biomass for the production of biofuels and value added products involves physical disruption of the polymeric linkages of lignocellulosic material which enhances the accessibility of lignocellulases and removes lignin. To investigate the impact of assorted pretreatments on structural changes, low lignin containing vegetable waste was selected as the biomass source. The combined effects of NaCl under different physical conditions on the biomass material were evaluated. Amounts of soluble sugars, monomeric phenols, holocellulose, inhibitors of hydrolysis and fermentation formed were determined. Physical and microstructural alterations of the material were analysed by XRD, FTIR and SEM. Accessibility of enzymes to the cellulose material was evaluated by quantifying the release of sugars in enzymatic hydrolysis for various pretreatment methods. The data revealed that pretreatment with NaCl is cost effective, ecofriendly and the process efficiency is comparable with common pretreatment methods like alkali, acid, ammonia, super critical fluid extraction etc. This is the first report on the use of sodium chloride for the pretreatment of vegetable waste.     

Titanium dioxide/cellulose nanocomposites prepared by a controlled hydrolysis method

TiO₂/cellulose nanocomposites were prepared through the titanyl sulphate hydrolysis in acidic medium in the presence of cellulosic fibres. The influence of several reaction parameters on the morphological characteristics of the nanocomposites was investigated. There is evidence from this study that in specific experimental conditions, the cellulose fibres promote the nucleation and growth of TiO₂ particles, yielding hybrid materials containing up to 46% TiO₂. Two series of paper handsheets having distinct TiO₂ content have been prepared, one from a selected hybrid composition and the other from mixtures of commercial TiO₂ and cellulose fibres. Comparative optical studies performed on the paper handsheets revealed a much higher opacity for the synthetic sample.     

A practical headspace gas chromatographic method for the determination of oxalate in bleaching effluents

This paper reports an improved headspace gas chromatographic (HS-GC) technique for the determination of oxalate content in bleaching effluents. The method is based on the redox reaction between potassium iodate and oxalate, from which the carbon dioxide is generated and measured by HS-GC. The results showed that the reaction in a sulfuric acid solution (0.05 mol/L) was complete in 35 min at 95 °C. The RSD of the method in the repeatability testing was less than 4.5%, the LOQ was 0.35 μg, and the recovery ranged from 95 to 103%. The present method is simpler, more reliable, and more practical compared to the methods reported previously.     

Influence of environmental stresses on the physicochemical stability of orange oil bilayer emulsions coated by lactoferrin–soybean soluble polysaccharides and lactoferrin–beet pectin

Based on layer-by-layer electrostatic deposition, orange oil bilayer emulsions stabilized with lactoferrin (LF)–soybean soluble polysaccharides (SSPS) and lactoferrin (LF)–beet pectin (BP) were prepared. The effect of environmental stresses (ionic strength, pH, freeze–thaw and light) on the physicochemical stability of primary and secondary emulsions was investigated. In the absence of anionic polysaccharides, orange oil emulsion was highly unstable and aggregated at pH 7–9 and NaCl of 0.1–0.5 M. The droplets in LF–SSPS coated emulsion were stable against aggregation at pH range of 3–10 and NaCl concentration less than 0.3 M, while the droplets in LF–BP coated emulsion were stable against aggregation at pH 4–9 and NaCl concentrations of 0–0.5 M. All the primary and secondary emulsions showed the instability after the freeze–thaw treatment and the stability could be improved in the presence of maltodextrin. During the light exposure (0.35 W/m², 45 °C) for 8 h, the bilayer emulsions could protect key volatile compounds (decanal, octanal and geranial) from the oxidation compared with the primary emulsions. These results suggested that the layer-by-layer electrostatic deposition could improve the stability of LF-coated emulsion to environmental stresses.     

Facile modification of thin-film composite nanofiltration membrane with silver nanoparticles for anti-biofouling

This study focuses on the modification of a commercial nanofiltration (NF) membrane by an in-situ reaction to load silver nanoparticles (AgNPs) for anti-biofouling. Poly (vinyl alcohol) (PVA) was coated onto the NF membrane firstly, and silver salt was then deposited on the surface of PVA layer. Through thermal reduction, AgNPs with 10–20 nm in diameter were formed and immobilized onto the membrane surface by the interaction between AgNPs and PVA, as confirmed by UV–vis absorption spectrum, SEM and XPS analysis. Compared to the pristine NF90 membrane, the PVA composite membranes (NF90-PVA) and AgNPs (NF90-PVA-AgNPs) modified membranes exhibit lower water flux and slightly higher salt rejection. Release of silver ion experiments were assessed via batch method, and the results indicate silver ion can be released from the AgNPs modified membrane continuously and steadily, which may be responsible for the improved and long-time antibacterial ability of the membrane. Due to the simplicity of the method, the ability to immobilize the AgNPs to avoid leaching out, and the strong antibacterial activity, this NF90-PVA-AgNPs composite membrane displays potential applications in industrial water-treatment.